You trade from Pokémon Emerald to Pokémon FireRed but to trade between these games, you must have done everything on all the Islands on FireRed which includes getting the Sapphire and Ruby stones, beating the Pokémon League and getting the National Pokédex on Pokémon Emerald.
You can't catch it, so you have to trade it from a game that has Rayquaza in it.
You can't get Rayquaza in Firered.
There is no way of getting it.
Rayquaza.
You can only get Rayquaza in Pokemon Ruby, Sapphire, and Emerald. If you want to get a Rayquaza in Pokemon Leafgreen or Firered, you will have to get a second Game Boy Advance or SP with a link cable to trade Rayquaza into your firered or leafgreen.
You must trade from Ruby, Sapphire or Emerald.
you trade rayquaza from Pokemon emerald(or other games depending which you have your rayquaza on) to fire red to get rayquaza on fire red, you can only do this after helping celio after cinnibar island gym
Rayquaza isn't in Fire Red/Leaf Green.
Groudon, Kyogre from sapphire, Rayquaza, Mewtwo from firered or leafgreen, Zapdos and Articuno again from firered and leafgreen.
Groudon, Kyogre, Rayquaza, Zapdos, Articuno, Mewtwo.
Rayquaza cannot be caught in Pokémon FireRed and LeafGreen. Trading it over from Pokémon Emerald is required. You must first obtain the National Pokédex from Professor Birch after beating the Elite Four, though.
i think its charizard (if choose) kyogre,groundon or rayquaza and dialga or palkia from dimond or pearl
Unfortunately the only real easy way to catch rayquaza is to use your master ball. if you really want to save it for Latias/Latios (Which you shouldn't because rayquaza is 10x better) is to paralyze him and then use the best ball you have in your inventory, but first you must get him down to low red in hp.